An optoelectronic device such as a photovoltaic cell, a light emitting diode (LED), or an organic light emitting diode (OLED) may include an encapsulant configured to encapsulate a light emission or light sensing region of the device.
For example, photovoltaic modules may be typically manufactured using a lamination process of laminating a transparent front substrate serving as a light receiving substrate, an encapsulant, a photovoltaic device, an encapsulant and a back sheet and then heat pressing the laminated body while applying a suction to the laminated body under a vacuum.
An ethylene-vinyl acetate (EVA) resin has been the most widely used as the encapsulant used for the photovoltaic modules in aspects of the processability, constructability, and cost.
However, the EVA resin exhibits low adhesive strength to elements, such as the front substrate or the back sheet, included in the optoelectronic device and coming in contact with the encapsulant. Therefore, when the modules are exposed to outdoor environments for a long period of time, they have a problem in that their delamination may occur easily. Also, in a method of manufacturing a photovoltaic module using an encapsulant including the EVA resin, the EVA resin may be thermally cracked under hot pressing conditions, resulting in the formation of acetic acid gas, etc. Such acetic acid gas causes problems in that it worsens working environments, has a negative influence on photovoltaic elements or electrodes included in the photovoltaic module, and also causes degradation of the modules and a decline in power generation efficiency, and the like.
Therefore, there is a continuous demand for encapsulants for optoelectronic devices having improved long-term adhesive properties.